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Bachmann On30 turn radius
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 Posted: Fri Mar 17th, 2017 09:52 pm
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Helmut F
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Lee,
I am researching, not looking into derailing of course. I found a New Mexico logging railroad that had some very tight bends. I am trying to figure out how tight from map data, but at the same time trying to figure out what I might be able to run and how tight on the layout.

I mentioned the locos I am interested in above, some go tighter than others. I do not even mind part of the layout for certain locos only - makes operations more interesting/challenging.

Right now it is all research and data to feed ideas, nothing more.



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 Posted: Fri Mar 17th, 2017 11:22 pm
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Kitbash0n30
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Look up book reprinted by Periscope Films, H. K. Porter Company Light Locomotives. Is reprint of Porter's catalog and includes full data on the various types and various sizes of each type - wheelbase, cylinder size, fuel and water capacity, boiler pressure, tractive force.
Example,
The class C-2-T Mogul was available in weights from 56,000 to 92,000 pounds. Could work on minimum rail weights from 30 to 50 pounds per yard.
Curve data is given for radius of sharpest curve advised, and radius of sharpest curve practicable.
The 56,000 pound loco's values for those are 165ft and 140ft.

The class 2-B-S-K, 0-4-2T, in its 15,500 pound version could do curve radius 60ft advised, 45ft sharpest practicable.
for the 53,000 pound version it was 100, and 70ft radius.

The little bitty class B-SS side tank 0-4-0 in 8,500 pound version is listed as sharpest curve advised 25ft radius; sharpest practicable 15ft radius. Lightest rail, 12 pounds per yard.
32,000 pound version gives 35ft and 18ft. Lightest rail, 30 pounds.
12 pounds per yard? Yard? Yeppers, it says per yard. That's practically strap iron!

A bunch of quirky locos in there I like. Such as the Class 2-C-R-K 0-6-2 big brother of Bachmann's 0-4-2. It is listed for 55 and 40ft curves in its smallest size.

ALSO - look at hauling capacity data and note how very sharply it drops as grade goes from level to 0.5% to 1% to 2% to 3%.

Example, 0-8-0 tender engine, 92,000 pounds.
level = 2,985 tons.
3% = 225 tons.
Less than a tenth of what it can pull on level.

And wrapping up by going back to the beginning, that class C-2-T Mogul which began this; for the 92,000 pound version,
on level = 2,770 tons
1% = 625 tons
3% = 205 tons.

And for those who complain their 4-4-0 ain't worth nuthin because it can only pull 7 cars up a 3% grade -->
Class B-4-T 4-4-0 passenger locomotive
85,000 pounds, 15x24 cylinders, 56 inch drives, 8ft wheelbase;
level = 1,950 tons
0.5% = 725 tons
3% = 130 tons.

I wonder how many rivet counters (on those other websites) get their shorts in a knot when modelers inaccurately model that? ;)
{actually, in past years there were a couple times I brought this up and apparently it got posted in invisible electrons only my ISP company could see - that was interesting}



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 Posted: Fri Mar 17th, 2017 11:31 pm
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Helmut F
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huh? what? did somebody post something?

:bg:



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 Posted: Fri Mar 17th, 2017 11:33 pm
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Helmut F
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sorry Kitbash - could not resist!

THAT seems like a cool book. Even if one does not model to that, the data seems interesting. Might have to get that one.



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 Posted: Fri Mar 17th, 2017 11:35 pm
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Kitbash0n30
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:D
And then there was the time at model RR club where I tried to convince the guys building the DCC-only layout that a 2% grade and a 2 degree slope were different things because percent and degree are different words with different meanings.
Okay, I've got my 4 DC modules for that layout, the DCC layout is not my problem, y'all have fun!



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 Posted: Sat Mar 18th, 2017 04:19 am
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jtrain
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I think what people are getting at here is that there are two radii to consider, minimum and practical.
Little 0-4-0 porters, can go on very narrow curves, down to 8 inch radius I'm told.  Joey Ricard's 2x4 micro layout from a couple years back proves that concept well.
But my 4-4-0 will definitely not do anything below 15 inch radius.  The lateral forces at play will force the wheels to jump the track.
The problem with minimum radii is that it isn't the complete story. The porter rounding 8 inch curves can't have long cars behind it, or even medium length cars.  2 axle or very short 4 axle cars are all that can be run.
Wheels and track determine minimum radii, but couplers and overhand determine practical radii. Practical radii is the minimum radius trains can perform reliable operations.Coupling, decoupling, switching, overhang, underhang (inside of the curve), and backing up cars often can't be done reliably on the minimum radius a locomotive can run.
Practical radii seems to be determined by the longest, bulkiest equipment on the roster. So then, I'd say figure out the biggest locomotives and the biggest cars you plan to run on the layout, but a couple for testing purposes, and build a layout around that.
As for degrees vs percent grade, a 2 degree angle is a 3.49% grade, pretty steep.
--James



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See progress on the Crown Peak Logging Railroad

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A blog with modeling ideas and prototype information about my favorite regional railroad, the Rapid City Pie
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 Posted: Sat Mar 18th, 2017 07:57 pm
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oztrainz
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Hi all,
James has hit the nail on the head. -  If you go pushing the edge of the minimum radius envelope then you will find that it is not just the locomotive that sets what you can tow/shove around any given radius. 

Surely the aim of the game is to have an enjoyable model that operates without problems. In the pdf link that was supplied previously, the first column or "minimum practical radius" is known to produce reliable operation. If you go for an "absolute minimum radius" as shown in the pdf for your locomotive and then your wagons have a larger "absolute minimum radius" then you will have problems because the sideways forces exerted at the couplings will exceed the forces that the flanges at the wheels can exert to keep your train on the tracks. 

Reg's point on clearances is also very valid as the radius comes down.  For bigger locomotives and longer cars anything above rail level near the tracks can become a "show-stopper" when impacted by end overhang on the outside of a curve or overhang in the middle of the wagon/loco on the inside of a curve. The bigger and longer the locomotive/wagon then a much wider "clear zone" is needed than for smaller rolling stock as the track radius decreases. This applies especially to things like switch stands on turnouts, roofs etc on structures close to the track. In industry they have switch stands where the throw lever folds flat just to get around this clearance problem. 


Just because you can go there probably doesn't mean that you should - when in comes to reliable operations of what can be some significantly large equipment in On30.  



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 Posted: Sat Mar 18th, 2017 11:53 pm
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Kitbash0n30
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oztrainz wrote: Just because you can go there probably doesn't mean that you should - when in comes to reliable operations of what can be some significantly large equipment in On30.  Bingo. As for me, my On30 is intended to be mostly quirky little things for streetcar radius curves, as clued by the name Willow Creek Traction.
There is some 6 axle power being built on Athearn SD7 mechanisms for which curves are a different ballgame.
Some examples of my tiny trains being; and there's not much to my layout, and with my health may not ever be more.










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 Posted: Sun Mar 19th, 2017 12:03 am
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Kitbash0n30
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oztrainz wrote: The bigger and longer the locomotive/wagon then a much wider "clear zone" is needed than for smaller rolling stock as the track radius decreases. This applies especially to things like switch stands on turnouts, roofs etc on structures close to the track. Yes, even my little 2 inch wide On30 pilots tag switch stands and especially the few remaining Atlas solenoid housings on club's modular HO layout except for
that one being moved away from usual attachment, and I don't know why, was previous club's work, will clear. That photo of the Plymouth bashes with the 2 inch wide pilots is from several years ago, pilots are now Chevy Engine Red with white V stripes.


My hot rod pink coal gondolas are Thomas Tank engine Troublesome Trucks purchased a decade ago at steep discount.
Some day the conductor will be allowed to come in from the wind and weather.



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 Posted: Mon Mar 27th, 2017 04:59 am
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Helmut F
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Guys,
another question or two along the lines of turn radius: what track separation is needed for parallel runs? is that number different on curves and straights?

I am looking to do a rough layout "by the squares" and want to get it correct.

Thx!

Last edited on Mon Mar 27th, 2017 04:59 am by Helmut F



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